Let me offer some anecdotal evidence of the 6100's performance, based on my subjective evaluations thus far and not on any objective measurements.
After having suffered through quite an ordeal at a Big Box store in the hopes of obtaining a significant markdown on a Sony VW40, I finally purchased the 6100 instead. In retrospect, I'm glad I did. I'm glad not only because of the 2 year warranty (instead of Sony's 1 year) but because, as they used to say of hot rods, "there's no replacement for displacement" and the Epson's 1800 lumens will drive this pj to quite large screen sizes in all reasonable conditions.
Even some unreasonable ones. My screen right now is in excess of 127" diagonal, and is projected on a bare wall painted dark brown. In dynamic mode the screen is plenty bright, with white balanced at 6500k and brightness turned down a couple of notches. With the iris set to "fast," the black levels are quite good. I do notice the iris action between scenes, but never within a scene. As some have commented, the iris motor is audible but for me won't be an issue with even quiet audio.
While the black levels won't be scaring any RS2s or Kuro plasmas, I find they compete nicely with my friend's Samsung plasma. This is perhaps unsurprising, given the dark finish of the unimproved projection surface. But the white levels are more than adequate here, even with what I would consider a great deal of ambient light. Playing Valkyria Chronicles whose manga style of graphics is deliberately reminiscent of Miyazaki's masterwork "Nausicaa," emphasizing pale watercolor-like palettes, the screen never appears washed out or dim. Even projecting on such a poor surface, the 6100 has the horsepower to run the large-ish screen size and maintain an appealing image.
And this isn't the projector's brightest mode! Switching to Living Room ups the brightness even further, at the expense of balancing the white levels at 8500k. Normally this is far too cold for any kind of even semi-critical viewing, but the dark brown wall color actually balances this out a bit, making the colors look far more natural. In dark or even dim viewing conditions, the brown wall notwithstanding, I find myself wincing from the brightness. In dynamic mode, I find the image watchable (though not necessarily in critical mode) with significant ambient light: with kitchen florescent lights spilling into the living room theater, and dining room halogens reflecting off of cream colored back walls into the theater as well. This is enough light to read by, comfortably. In Living Room mode, however, all but direct lighting is easily handled.
Without having taken any measurements, a quick analysis of the 6100's projection of my MacBook Pro's display suggests that the color palette runs on the intense side, with colors generally oversaturated. My "testing" in this regard was limited primarily to Dynamic and Living Room modes, and color variation here is to be expected. However, even in these modes, viewing color intense films such as "300" appeared reasonably natural in my theater. There are, additionally, a number of available tweaks to control color, brightness, sharpness, and other aspects of the projected image. With something like 20 memory slots to save settings, tweakers have a lot to play with here.
Lastly, let me mention the remote. With direct access to all input modes, real back-lighting, and quickly navigable menu modes, I think most users will appreciate it as a superior remote for an entry-level 1080p pj.